java io学习

下图是java.io输入流的uml图


InputStream是表示字节输入流的所有类的超类。

需要定义 InputStream 子类的应用程序必须总是提供返回下一个输入字节的方法。
ByteArrayInputStream类使用

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Scanner;

public class ByteArrayTest {
	public static void main(String[] args) {
		try {
			File file = new File(System.getProperty("user.dir")+File.separator+"test.txt");
			BufferedInputStream buffer = new BufferedInputStream(new FileInputStream(file));
			ByteArrayOutputStream arrayOutPutStream = new ByteArrayOutputStream();
			byte[] bytes = new byte[1];
			while(buffer.read(bytes)!=-1)
			{
				arrayOutPutStream.write(bytes);
			}
			arrayOutPutStream.close();
			buffer.close();
			bytes = arrayOutPutStream.toByteArray();
			for (byte b : bytes) {
				System.out.print((char)b);
			}
			
			System.out.println();
			Scanner scanner  = new Scanner(System.in);
			System.out.print("输入修改的位置:");
			int pos = scanner.nextInt();
			System.out.print("输入修改的字符:");
			bytes[pos-1]=(byte)scanner.next().charAt(0);
			ByteArrayInputStream arrayInputStream = new ByteArrayInputStream(bytes);
			System.out.println("测试此 InputStream 是否支持 mark/reset:"+arrayInputStream.markSupported());
			BufferedOutputStream bufferOutput = new BufferedOutputStream(new FileOutputStream(file));
			byte temp[] = new byte[1];
			while(arrayInputStream.read(temp)!=-1)
			{
				bufferOutput.write(temp);
			}
			
			arrayInputStream.close();
			bufferOutput.flush();
			bufferOutput.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		}catch (IOException e) {
			e.printStackTrace();
		}
		
	}
}